Method of printing document based on black optimization printing option and image forming apparatus and host device to perform the same

ABSTRACT

A method of controlling an image forming apparatus supporting a black optimization printing option in a host apparatus includes executing a printer driver of the image forming apparatus, setting the black optimization printing option in a user interface of the executed printer driver, generating a second color matching table by using an existing first color matching table and color properties corresponding to red, blue, and green values of a document to be printed based on the set black optimization printing option, selecting a first printing method to print the document by using the first color matching table or a second printing method to print the document by using the second color matching table, based on the red, green, and blue values of the document, and transmitting the document and print data of the document to which a color matching table corresponding to the selected printing method is applied to the image forming apparatus.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. §119(a) of KoreanPatent Application No. 10-2009-0079479, filed on Aug. 26, 2009, in theKorean Intellectual Property Office, the disclosure of which isincorporated herein in its entirety by reference.

BACKGROUND

1. Field of the Invention

The present general inventive concept relates to a method of printing adocument based on a black optimization printing option and an imageforming apparatus and a host device to perform the method.

2. Description of the Related Art

An image forming apparatus performs one or more of functions withrespect to a document. Such functions include printing, copying,scanning, sending/receiving a fax, sending an e-mail, and sending a fileto a server. When a user prints a document via an image formingapparatus, the user may set up a printing option, which is either acolor printing option or a black/white (monochrome) printing option. Theimage forming apparatus performs color printing or black-and-whiteprinting based on the set printing option. In the case where the colorprinting option is activated, if a portion of a document includes acolor other than black, an image forming apparatus performs a printingtask by combining cyan, magenta, yellow, and black.

SUMMARY

The present general inventive concept provides a method of printing adocument based on a black optimization printing option and an imageforming apparatus and a host device to perform the method. However, thepresent general inventive concept is not limited to the above features,and additional features and/or utilities may be achieved by a method,apparatus, and host device according to the present general inventiveconcept.

Additional features and utilities of the present general inventiveconcept will be set forth in part in the description which follows and,in part, will be obvious from the description, or may be learned bypractice of the general inventive concept.

Features and/or utilities of the present general inventive concept maybe realized by a method of controlling an image forming apparatussupporting a black optimization printing option in a host apparatus, themethod including executing a printer driver of the image formingapparatus, setting the black optimization printing option in a userinterface of the executed printer driver, generating a second colormatching table by using an existing first color matching table and colorproperties corresponding to red, blue, and green values of a document tobe printed based on the set black optimization printing option,selecting a first printing method to print the document by using thefirst color matching table or a second printing method to print thedocument by using the second color matching table, based on the red,green, and blue values of the document, and transmitting the documentand print data of the document to which a color matching tablecorresponding to the selected printing method is applied to the imageforming apparatus.

Features and/or utilities of the present general inventive concept mayalso be realized by a method of printing a document based on a blackoptimization printing option in an image forming apparatus connected toa host apparatus, the method including receiving the document andinformation regarding the black optimization printing option from thehost apparatus, generating a second color matching table by using anexisting first color matching table and color properties correspondingto red, blue, and green values of the document based on the receivedinformation regarding the black optimization printing option, selectinga first printing method to print the document by using the first colormatching table or a second printing method to print the document byusing the second color matching table based on values of red, green, andblue of the received document, and printing the document by using thefirst color matching table or the second color matching table accordingto the selected method.

Features and/or utilities of the present general inventive concept mayalso be realized by an image forming apparatus, which is connectable toa host apparatus and supports a black optimization printing option, theimage forming apparatus including a communication interface unit toreceive a document to be printed and information regarding the blackoptimization printing option from the host apparatus, a generating unitto generate a second color matching table by using an existing firstcolor matching table and color properties corresponding to red, blue,and green values of the document based on the received informationregarding the black optimization printing option, a control unit whichcontrols the image forming apparatus such that print data to whicheither the first color matching table or the second color matching tableis applied is printed by the image forming apparatus, a storage unit tostore the received document and the generated second color matchingtable, a selecting unit to select a first printing method to print thedocument by using the first color matching table or a second printingmethod to print the document by using the second color matching tablebased on values of red, green, and blue of the received document, and animage forming unit to print the document by using the first colormatching table or the second color matching table based on the selectedmethod.

Features and/or utilities of the present general inventive concept mayalso be realized by a host apparatus to control an image formingapparatus supporting a black optimization printing option, the hostapparatus including a user interface unit which receives information toset the black optimization printing option by using a printer driver ofthe image forming apparatus, a processor which executes the printerdriver of the image forming apparatus, generates a second color matchingtable by using an existing first color matching table and colorproperties corresponding to red, blue, and green values of a documentbased on the selection of the black optimization printing option, andselects a first printing method to print the document by using the firstcolor matching table or a second printing method to print the documentby using the second color matching table, and a communication interfaceunit which transmits the document and print data of the document towhich a color matching table corresponding to the selected printingmethod is applied to the image forming apparatus.

Features and/or utilities of the present general inventive concept mayalso be realized by a method of forming an image including generating asecond color-matching table corresponding to a first color-matchingtable, the values of the second color-matching table based on values ofa plurality of colors in a document and the values of the firstcolor-matching table corresponding to predetermined levels of the colorsdivided into a predetermined number of intervals, each intervalcorresponding to an intensity of each color, respectively, and printingthe document using the second color-matching table when the colors inthe document are below a predetermined threshold.

Generating the second color-matching table may include assigning aweight to each of the values of the first color-matching table tocorrespond to the intensity of each color in the document, such that thevalues of the second color-matching table are the weighted values of thefirst color-matching table.

The predetermined threshold may include a plurality of thresholds, andgenerating the second color-matching table may include dividing thesecond color-matching table into a plurality of regions defined by theplurality of thresholds, respectively, the values of each regioncorresponding to a different weight than the values of each otherregion.

The weight may include a first weight value and a second weight value,the first weight value corresponds to a percentage applied to the valuesof the colors of the first color-matching table to generate thecorresponding values of the colors of the second color-matching table,and the second weight value corresponds to a percentage applied to avalue of at least one of the colors of the first color-matching table togenerate a monochrome color value of the second color-matching table.

The first weight value may decrease as the values of the colors of thefirst color-matching table decrease, and the second weight value mayincrease as the values of the colors of the first color-matching tabledecrease.

The value of the at least one of the colors of the first color-matchingtable used to generate a monochrome color value of the secondcolor-matching table may include an average of the values detected inthe document of each color of the first color-matching table.

The monochrome color may be black.

The first color-matching table may include values of the colors red,green, and blue.

The first color-matching table may include values of the colors cyan,magenta, yellow, and black.

The method may include determining color intensities of a plurality ofregions of the document, and printing each respective region of thedocument using the second color-matching table only when the colors inthe respective region are below the predetermined threshold.

The method may include printing each respective region of the documentusing the first color-matching table only when the colors in therespective region are equal to or greater than the predeterminedthreshold.

Features and/or utilities of the present general inventive concept mayalso be realized by a method of printing an image including receiving aninput to perform a monochrome-color optimization function on a document,generating a second color-matching table corresponding to a firstcolor-matching table, the values of the second color-matching tablebased on values of a plurality of colors in the document and the valuesof the first color-matching table corresponding to predetermined levelsof the colors divided into a predetermined number of intervals, eachinterval corresponding to an intensity of each color, respectively,determining whether the levels of the colors in the document exceed apredetermined threshold, and transmitting the second color-matchingtable with print data of the document only when the colors in thedocument do not exceed the predetermined threshold, and transmitting thefirst color-matching table with the print data of the document only whenthe colors in the document exceed the predetermined threshold.

Features and/or utilities of the present general inventive concept mayalso be realized by a method of printing an image including generating asecond color-matching table corresponding to a first color-matchingtable, the values of the second color-matching table based on values ofa plurality of colors in a document and the values of the firstcolor-matching table corresponding to predetermined levels of the colorsdivided into a predetermined number of intervals, each intervalcorresponding to an intensity of each color, respectively, determiningwhether the levels of the colors in the document exceed a predeterminedthreshold, and printing the document using the second color-matchingtable only when the colors in the document do not exceed thepredetermined threshold, and printing the document using the firstcolor-matching table only when the colors in the document exceed thepredetermined threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and utilities of the present generalinventive concept will become more apparent by describing in detailexemplary embodiments thereof with reference to the attached drawings inwhich:

FIG. 1 is a schematic view of an image forming system according to anembodiment of the present general inventive concept;

FIG. 2 is a diagram showing a user interface screen to select a printingoption according to an embodiment of the present general inventiveconcept;

FIG. 3 is a diagram showing an add-combining method of embodying colorsby using the RGB color model;

FIG. 4 is a diagram showing a subtract-combining method of embodyingcolors by using the CMY color model;

FIG. 5A is a diagram showing a method of setting regions based on athreshold value according to an embodiment of the present generalinventive concept; FIGS. 5B and 5C illustrate conversions of a firstcolor table to a second color table;

FIG. 6 is a flowchart of a data process performed by a control unitbased on selection of the black optimization printing option accordingto an embodiment of the present general inventive concept;

FIGS. 7A and 7B are flowcharts of data process for an individual objectbased on selection of the black optimization printing option accordingto an embodiment of the present general inventive concept;

FIG. 8 is a flowchart of a method of controlling an image formingapparatus which supports the black optimization printing optionaccording to an embodiment of the present general inventive concept

FIGS. 9A and 9B illustrate regions of a document according to anembodiment of the present general inventive concept.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the embodiments of the presentgeneral inventive concept, examples of which are illustrated in theaccompanying drawings, wherein like reference numerals refer to the likeelements throughout. The embodiments are described below in order toexplain the present general inventive concept by referring to thefigures.

FIG. 1 is a schematic view of an image forming system according to anembodiment of the present general inventive concept. Referring to FIG.1, the image forming system according to an embodiment of the presentgeneral inventive concept includes a host apparatus 100 and an imageforming apparatus 200. Although the image forming system according to anembodiment of the present general inventive concept includes only onehost apparatus 100 and one image forming apparatus 200, the imageforming apparatus 200 may be connected to a plurality of hostapparatuses 100.

For clarity of the description, only components related to an embodimentof the present general inventive concept will be explained. Therefore,it will be understood by one of ordinary skill in the art that othergeneral components other than the components shown in FIG. 1 may befurther included in an image-forming system.

Referring to FIG. 1, the host apparatus 100 includes a user interfaceunit 110, a driver module 120, a processor 130, and a communicationinterface unit 140. The host apparatus 100 is an apparatus to controlthe image forming apparatus 200, and may be any device that may beconnected to the image forming apparatus 200 and control the imageforming apparatus 200, such as a general purpose computer system and apersonal digital assistant (PDA).

The user interface unit 110 obtains an input signal from a user anddisplays output information to the user. For example, if the hostapparatus 100 is a general purpose computer system, the host apparatus100 includes input/output devices, such as a mouse, a keyboard, amonitor, and a speaker.

A user operates the user interface unit 110 to select a document to beprinted and sets up printing options to print the selected document. Ina method of setting up a printing option, a user initiates anapplication, opens a document to be printed by the image formingapparatus 200 via the initiated application, and executes a printerdriver of the driver module 120 to perform a printing task. The printerdriver may be executed by, for example, clicking a printing icon. Whenthe printer driver is executed, a user interface screen to set up aprinting option is displayed on the user interface unit 110.

FIG. 2 is a diagram showing a user interface screen to select a printingoption according to an embodiment of the present general inventiveconcept. Referring to FIG. 2, a printing option setup screen 111 isdisplayed on the user interface unit 110 (e.g., the monitor) of the hostapparatus 100. The printing option setup screen 111 may be displayedwhen the printer driver is executed. A user may select to print usingnormal color settings, a monochrome setting, or a black optimizationprinting option according to an embodiment of the present generalinventive concept. The black optimization setting may be activated, set,or selected by selecting “black optimization” option 113 in “graphic”tab 112, for example.

In the present specification and claims, “monochrome” may referparticularly to black and shades of black (i.e. gray). However, themonochrome color need not be limited to black, and may instead be red,green, blue, cyan, magenta, yellow, or any other desired color.

The printing option setup screen 111 shown in FIG. 2 is merely anexample of a user interface to set up a printing option according to anembodiment of the present general inventive concept, and the presentgeneral inventive concept is not limited thereto.

In a printing method based on black optimization, a document is printedby using only black color only when red, green, and blue colors in thedocument are close to a monochrome value. In addition, a level of blackcolor used may be increased as the levels of red, green, and blueapproach monochrome color.

The printing option setup screen 111 shown in FIG. 2 illustrates anexample of an option setup screen when the monochrome color is black. Inother words, when a user selects the “black optimization” option 203,the image forming apparatus 200 prints regions formed of colors close tomonochrome values (i.e. black and shades of gray) by using black coloronly.

The user may conveniently set up a printing option by using the hostapparatus 100. In other words, the user may input an instruction toexecute the printer driver by using the user interface unit 110, andalso may select the black optimization printing option in the userinterface displayed in response to executing the printer driver.

The communication interface unit 140 transmits a document to be printedand print data in which the selected black optimization printing optionis included to the image forming apparatus 200, and the image formingapparatus 200 prints the document based on the black optimizationprinting option under control of the host apparatus 100. When the blackoptimization printing option is selected, the user may efficiently printthe document using only a black toner without using other toners. Inaddition, the user may efficiently print the document using multiplecolors, but portions of the document that are monochrome or nearmonochrome may be printed using only black toner to conserve othertoners. Furthermore, since the image forming apparatus 200 may becontrolled by using the host apparatus 100, user convenience may beimproved.

Referring back to FIG. 1, the driver module 120 includes one or moreprograms to control the image forming apparatus 200. The driver module120 may include software stored in a data storage device. The drivermodule 120 according to an embodiment of the present general inventiveconcept includes a printer driver, a scan driver, etc. As describedabove, a printer driver converts a document composed by an applicationof the host apparatus 100 into print data that may be interpreted by theimage forming apparatus 200 to print the document via the image formingapparatus 200. For example, a printer driver includes a graphic deviceinterface (GDI) driver, a postscript driver, a print command language(PCL) driver, and a XML paper specification (XPS) driver.

The printer driver according to an embodiment of the present generalinventive concept may further include a web application to control theimage forming apparatus 200. The web application may provide a web userinterface to control the image forming apparatus 200. The user mayselect by using the host apparatus 100 a printing option via a web userinterface provided by the printer driver of the driver module 120.

The processor 130 controls the image forming apparatus 200 via the hostapparatus 100. In other words, the processor 130 executes the printerdriver of the driver module 120 and displays the user interface inresponse to the execution of the printer driver on the user interfaceunit 110. Furthermore, the processor 130 controls overall functions ofthe host apparatus 100. The processor 130 may be a processor chip,multiple processor chips, or a combination of one or more processorchips, logic circuits, and memory.

The host apparatus 100 may control the image forming apparatus 200 toperform a printing task based on a black optimization printing option bysetting the black optimization printing option and transmitting only theset printing option information to the image forming apparatus 200.

Furthermore, the host apparatus 100 may transmit print data in which theselected optimization printing option is included to the image formingapparatus 200. For example, when a full-color option is selected, theprocessor 130 of the host apparatus 100 executes the printer driver andmay generate or utilize a pre-existing first color matching table toconvert document or image data to print data. When a user selects theblack-optimization setting, the processor 130 generates a second colormatching table based on the existing first color matching table andcolor properties corresponding to values of red, green, and blue colorsof the document to be printed. The processor 130 may then select eithera first printing method to print the document by using the first colormatching table or a second printing method to print the document byusing the second color matching table according to values of red, green,and blue colors in the document.

The communication interface unit 140 transmits the document to beprinted and print data of the document including the color matchingtable corresponding to the selected printing method to the image formingapparatus 200.

Each of the first and second color-matching tables may be stored ineither one of the host apparatus 100 and the image-forming apparatus200. For example, the first color matching table may be stored in thehost apparatus 100, whereas the generated second color matching tablemay be stored in the host apparatus 100. The second color matching tablemay be used once corresponding to one document, or it may be stored andused repeatedly.

In addition, the operation to generate the second color matching tablecorresponding to the second printing method and selecting either thefirst printing method or the second printing method may be performed bythe image forming apparatus 200. In other words, either the hostapparatus 100 or the image forming apparatus 200 may generate the colormatching table corresponding to a second printing method and may selecteither the first printing method or the second printing method. Then,the image forming apparatus 200 performs a printing task by using thecolor matching table corresponding to the selected printing method. Themethod of generating the second color matching table and the method ofselecting either the first printing method or the second printing methodwill be described in relation to the image forming apparatus 200 belowin detail.

The communication interface unit 140 transmits and receives data to andfrom the image forming apparatus 200 via a network. A network accordingto an embodiment of the present general inventive concept may be a wirednetwork or a wireless network, and the communication interface unit 140may include one or more wired ports or wireless antennae. Examples ofthe network include internet, a local area network (LAN), a wirelessLAN, and a wide area network (WAN). However, an embodiment of thepresent general inventive concept is not limited thereto, and it will beunderstood by one of ordinary skill in the art that any type of networkcapable of transmitting and receiving data may be utilized.

Referring to FIG. 1, the image forming apparatus 200 includes acommunication interface unit 210, a control unit 220, a storage unit230, a generating unit 221, a selecting unit 222, a user interface unit240, an image forming unit 251, a faxing unit 252, and a transmissionperforming unit 253.

The image forming apparatus 200 is connected to one or more hostapparatuses 100 in a wired or wireless manner, and supports one or morefunctions with respect to a document. The functions include printing,copying, scanning, sending/receiving a fax, sending an e-mail, andsending data to a server.

The communication interface unit 210 receives from the host apparatus100 via a network one or more pieces of print data, which designates adocument to be printed, and print data in which a selected printingoption is included. The communication interface unit 210 includes amodule to transmit and receive a fax, a network module to be connectedto a network, and a USB host module to form a data movement channel withrespect to a mobile storage medium.

As described above in relation to the host apparatus 100, thecommunication interface unit 210 receives one or more pieces of printdata and printing option information that are transmitted by thecommunication interface unit 140 of the host apparatus 100. When printdata in which the selected black optimization printing option isincluded is received from the host apparatus 100, the image formingapparatus 200 prints the document based on the selected blackoptimization printing option according to an embodiment of the presentgeneral inventive concept.

However, printing option information may be either received from thehost apparatus 100 or directly input via the user interface unit 240 ofthe image forming apparatus 200. For example, when the user wants toperform a task such as copying a document, the user may select printingoption information by selecting input icons displayed as a graphic userinterface (GUI) on a display panel of the user interface 240.

Furthermore, the communication interface unit 210 may receive from thehost apparatus 100 print data including a color matching table. In thiscase, the control unit 220 may perform a printing task according to theselected black optimization printing option based on the received printdata in the image forming unit 251.

The control unit 220 controls overall operations of the image formingapparatus 200. In other words, the control unit 220 controls thecommunication interface unit 210, the storage unit 230, the generatingunit 221, the selecting unit 222, the user interface unit 240, an imageforming unit 251, the faxing unit 252, and the transmission performingunit 253. Also, the control unit 220 prints print data based on setprinting option information. The control unit 220 may include one ormore processors, supporting logic chips, and memory.

If the black optimization printing option is activated, the control unit220 controls the image forming apparatus 200 such that print data towhich a color matching table based on the values of red, green, and blueof a document to be printed is applied is printed via the image formingunit 251.

When the black optimization printing option is activated, the controlunit 220 sets one or more regions in the document based on how close thevalues of red, green, and blue colors of a document to be printed are tomonochrome values, the generating unit 221 generates a color matchingtable based on the values of red, green, and blue colors of thedocument, and the selecting unit 222 selects either a first printingmethod to print the document by using an existing color matching tableor a second printing method to print the document by using the generatedcolor matching table. In this case, the selected first printing methodor second printing method may be applied to the entire document, or eachof the set one or more regions in the document. Hereinafter, forconvenience of explanation, an existing color matching table will bereferred as a first color matching table, and a color matching tablegenerated by the generating unit 221 will be referred as a second colormatching table.

The values of red, green, and blue colors of a document to be printedwill be described below in more detail. Although the most accuratemethod of embodying colors is using frequency band graphs with respectto all colors, it is not efficient to calculate the frequency bandgraphs for all colors that are to be successively embodied. Thus,various methods may be used to embody colors, and such methods arereferred to as color models. Examples of color models include the RGB(red, green, and blue) model and the CMY (cyan, magenta, and yellow)model.

FIG. 3 is a diagram showing an add-combining method of embodying colorsby using the RGB color model. The RGB color model embodies colors byusing three primary colors. The RGB color model is based on the additivesystem in which colors becomes brighter as more colors are mixed, andcolors are obtained by mixing red 301, green 302, and blue 303.

FIG. 4 is a diagram showing a subtract-combining method of embodyingcolors by using the CMY color model. The CMY color model is based on thesubtractive system used in many printing devices, and the primary colorsof the CMY color model are cyan 401, magenta 402, and yellow 403. Thebasic colors of the CMY color model, the cyan 401, the magenta 402, andyellow 403, are complementary colors with respect to the red 301, thegreen 302, and the blue 303 of RGB color model. A printing deviceembodies colors by using three color toners containing the cyan 401, themagenta 402, and the yellow 403, respectively. However, since pure blackcannot be embodied by mixing the cyan 401, the magenta 402, and theyellow 403 in the CMY color model, the CMYK color model, which is theCMY color model to which black (K) 404 is added, is also used.

Referring back to FIG. 1, although the image forming apparatus 200 mayperform a printing task by using various color models, it is assumedbelow for convenience of explanation that a printing task is performedby using the CMYK color model. However, an embodiment of the presentgeneral inventive concept is not limited thereto and may also be appliedto the case when a printing task is performed by using inks.

If each of values of the R, G, and B colors are represented as 8-bitdata in the RGB color model, values of red, green, and blue colors of adocument to be printed may be expressed in the form (16, 15, 16) whenthe value of R color corresponds to 16, the value of G color correspondsto 15, and the value of B color corresponds to 16. In this case, thevalues of the R, G, and B colors are representing the intensities ofred, green, and blue of the document to be printed. Thus, the values ofthe R, G, and B colors encoded in 24 bits per pixel (bpp) are specifiedusing three 8 bit unsigned integers (e.g., from 0 to 255) representingthe intensities of red, green, and blue. Further, color properties of adocument to be printed may be decided based on the values of the red,green, and blue colors that are expressed in the above form.

When print data is received from the host apparatus 100, the controlunit 220 converts the received print data into image data via anemulation process, and renders the converted image data. Examples of theemulation process according to an embodiment of the present generalinventive concept include printer control language (PCL), HP graphiclanguage (HPGL), printer description language (PDL), KS/KSSM, postscript(PS), SML paper specification (XPS), and PCL5CE.

Furthermore, the control unit 220 may convert not only print datareceived from the host apparatus 100, but also fax data received from afax apparatus and data received from a movable storage medium connectedto the image forming apparatus 200 into image data by using theemulation process. Although the format of image data is generallybitmap, the format of image data is not limited thereto, and examples ofthe format of image data include joint photographic experts group(JPEG), graphic interchange format (GIF), and portable network graphics(PNG).

The control unit 220 renders converted image data. The term renderingrefers to converting colors of each of pixels of the converted imagedata into print data according to the respective colors.

Furthermore, the control unit 220 sets one or more regions in thedocument based on how close the values of the red, green, and bluecolors of a document are to monochrome values. The one or more regionsmay include a first region, a second region, and a third region based onhow close the values of the red, green, and blue colors of the documentare to monochrome values.

The control unit 220 compares the values of the red, green, and bluecolors of each pixel of a document to be printed to a predeterminedcritical value, and determines the color properties of the documentaccording to how close the values of the red, green, and blue colors areto monochrome values. As described above, when the values of the red,green, and blue colors of a pixel are (0, 0, 0), respectively, the coloris black. The control unit 220 analyzes the values, compares the resultof the analysis to a predetermined critical value, and determines thecolor properties based on how close the colors of each pixel are tomonochrome values.

The predetermined critical value may be set as a ratio from 0% to 100%,or a value from 0 to 255 (in the case of using 8-bit data) may be setbased on the channel values of each color. However, the predeterminedcritical value described above is merely an example. Hereinafter, amethod of setting regions based on the predetermined critical value willbe described in closer detail.

When a document to be printed includes colors other than black, theprinting quality deteriorates if a printing task is performed by usingmixed colors throughout the document. In other words, if a text objectembodied by using black only and objects embodied by using colors otherthan black coexist in a document to be printed, a printing task may beperformed by using all the colors and by mixing colors in the document.Therefore, a printing task is performed not by using a black toner, butby mixing color toners including cyan, magenta, and yellow for not onlyobjects including colors other than black, but also for text objectsembodied by using black or a color close to monochrome values. Accordingto this method, it is necessary to stop and restart anelectro-photograph processor engine to perform a monochrome printingmethod, which is used to print by using black only during a printingtask using a mixed color printing method, and thus the printing speeddecreases.

Therefore, the image forming apparatus 200 according to an embodiment ofthe present general inventive concept analyzes values of the red, green,and blue of colors constituting a document and prints regions of whichcolors are close to monochrome values by using a black toner. Thus, thecontrol unit 220 compares a mixture degree of the red, green, and bluecolor of each pixel of print data to the predetermined critical value,and sets one or more regions in the document based on a comparisonresult.

For example, the control unit 220 may divide color levels of a documentto be printed into three regions. When the three regions according to anembodiment of the present general inventive concept are referred to as afirst region, a second region, and a third region, the first regionrefers to a region embodied by a color closest to monochrome values, andthe third region refers to a region embodied by a color farthest frommonochrome values. The boundary between the first region and the secondregion may be set using a first threshold value, and the boundarybetween the second region and the third region may be set using a secondthreshold value.

FIG. 5A is a diagram showing a method of setting regions based on athreshold value according to an embodiment of the present generalinventive concept. Referring to FIG. 5A, a color table 501 to representabout 4,913 colors and an interest region graph 502 regarding aninterest region set based on threshold values are shown.

In case where each value of the R, G, and B colors of a document to beprinted is represented as 8-bit data, each of the R, G, and B colors mayhave a value from 0 to 255, and 16,777,216 colors in total may berepresented by combining the R, G, and B colors. The image formingapparatus 200 may use various color tables to represent these colors.Each of the R, G, and B colors may be divided into 9, 17, or 33 regionsand each of the values from 0 to 255 may correspond to these regions.The color table 501 represents about 4,913 colors by dividing each ofthe R, G, and B colors into 18 regions.

The interest region graph 502 shows interest regions set incorrespondence to the color table 501. The interest region graph 502 isshown based on the R, G, and B axis. It is assumed that the interestregion includes a first region 503, a second region 504, and a thirdregion 505.

According to conditions for using the image forming apparatus 200,colors having values equal-to or less-than the first threshold value maybe in the first region 503, and colors having values greater than thefirst threshold value and equal-to or less-than the second thresholdvalue may be in the second region 504. All other regions except thefirst region 503 and the second region 504 may correspond to the thirdregion 505, or a size of the third region 505 may be designated byseparately setting a third threshold value.

The first threshold value, the second threshold value, and the thirdthreshold value may be set according to conditions for using the imageforming apparatus 200. For example, the first threshold value may be setas second section (No. 2) in the color table 501, and the secondthreshold value may be set as tenth section (No. 10) in the color table501. For example, a region in which values (R, G, B) are (5, 6, 8) maybe in the first region.

Referring back to FIG. 1, the control unit 220 sets the first and secondthreshold levels to define the first, second, and third regions.

The first through third regions and the first and second thresholdvalues described above are merely examples according to an embodiment ofthe present general inventive concept, and the number of regions andthreshold values are not limited to the above description.

The generating unit 221 may generate a second color matching table byusing an existing first color matching table and color propertiescorresponding to values of the red, green, and blue colors of thedocument. In other words, the control unit 220 sets one or more regionsin the document, and the generating unit 221 generates a color matchingtable corresponding to the set regions. The generating unit 221 may bepart of the control unit 220 and may include software executed by thecontrol unit 220 to generate the second color-matching table.

In an embodiment of the present general inventive concept, the term“color matching table” refers to a table including correspondingrelationships among composition ratios of primary colors and black inorder to represent a color with respect to a plurality of the primarycolors and black corresponding to toners of the image forming apparatus200. In other words, a color matching table in the image formingapparatus 200 according to an embodiment of the present generalinventive concept refers to a table including correspondingrelationships among composition ratios of cyan, magenta, yellow, andblack to represent a color by mixing cyan, magenta, yellow, and black.However, the color matching table may include other various colors. Acolor matching table according to an embodiment of the present generalinventive concept may be stored in the storage unit 230 as a lookuptable, for example. Alternatively, the color-matching table may bestored in the host apparatus 100.

The generating unit 221 generates a second color matching tablecorresponding to the set regions by using the first color matching tablestored in the storage unit 230. In other words, the generating unit 221generates the second color matching table by multiplying a first colormatching table by a weight corresponding to color properties of thedocument.

The second color matching table may be formed of color matching tablesrespectively corresponding to set regions. In other words, the secondcolor matching table may include a color matching table corresponding tothe first region, a color matching table corresponding to the secondregion, and a color matching table corresponding to the third region.

The color properties are relative printing values with respect to cyan,magenta, yellow, and black in regions set based on how close the valuesof red, green, and blue colors are to monochrome values, and therelative printing values are weighted values based on the values of red,green, and blue of the document which are closer to monochrome values.The relative printing values comprises a first value and a second value.In this case, the first value is a weight value assigned to color valueswith respect to cyan, magenta, and yellow values, and the second valueis a weight value assigned to black value. In other words, the relativeprinting values may be determined such that the second value increasesand the first value decrease as values of the red, green, and bluecolors of a document are closer to monochrome values.

For example, a document to be printed according to an embodiment of thepresent general inventive concept may include a first region containingcolors closest to monochrome values and second and third regionscontaining colors other than black. In this case, colors of the secondregion are closer to monochrome values than colors of the third region.

Since the first region contains colors which value is the closest tomonochrome values, the generating unit 221 generates a second colormatching table with respect to the first region by setting a first valueto 100% and also setting a second value to 0% with respect to a firstcolor matching table.

In particular, a first color matching table indicates mixture ratio withrespect to each of cyan, magenta, yellow, and black. The generating unit221 generates a second color matching table by multiplying mixture ratioin the first color matching table by the relative printing values. Inother words, the generating unit 221 generates the second color matchingtable by multiplying the first value by values of colors with respect tomixture ratio of cyan, magenta, and yellow of the first color matchingtable and multiplying the second value by value of black.

The generating unit 221 may generate the second color matching tablewith respect to the second region by setting a second value to 70% andsetting a first value to 40%, and may also generate the second colormatching table with respect to the third region by setting a secondvalue to 30% and setting a first value to 80%. The relative printingvalues may be changed by a user or according to setting of the imageforming apparatus 200. Thus, the first value and the second value may bechangeable.

FIGS. 5B-5D illustrate methods of determining whether a color of a firstcolor-matching table exceeds a predetermined threshold and generating asecond color-matching table.

In FIG. 5B, the closeness of a CMYK color to a monochromatic color isdetermined by averaging the CMY values of the color from the firstcolor-matching table 511. For example, if the host apparatus 100determines that pixel no. 1 of a document has CMY values of 8, 0, and12, respectively, the host apparatus 100 may calculate an average CMYvalue of 5. If the first threshold value is 16, corresponding to theinterval No. 2 of color table 501, then the pixel no. 1 of the firstcolor-matching table 511 falls into the first region. If the firstweight value of the first region is set at 0% and the second weightvalue is set at 100%, then the values corresponding to the colors CMYare all 0 in the second color-matching table 521, and the valuecorresponding to black, K, is 10.

Likewise, if a second threshold level is set at 112 to correspond tointerval No. 8 of the color table 501, then the host apparatus 100 maydetermine whether a pixel value falls into the second region if anaverage CMY value is less-than or equal-to 112. Since the average CMYvalues of pixels 2, 3, and 4 of the first color-matching table 511 areall between 16 and 112, each of the pixels 2, 3, and 4 would correspondto the second region. If the first weight value of the second region isset at 40% and the second weight value is set at 70%, then the valuescorresponding to the colors CMY may all be multiplied by 0.4 in thesecond color-matching table 521, and the value corresponding to black,K, may be multiplied by 0.7.

Since pixels 4 and 5 have average CMY values above the second thresholdlevel, 112, the host apparatus 100 may determine that pixels 4 and 5 arelocated in the third region. If the first weight value of the thirdregion is set at 80% and the second weight value is set at 30%, then thevalues corresponding to the colors CMY may all be multiplied by 0.8 inthe second color-matching table 521, and the value corresponding toblack, K, may be multiplied by 0.3.

FIG. 5C is similar to FIG. 5B, except the closeness of the CMYK pixel toa monochrome color, black, is determined by the highest CMY value eachpixel, rather than by an average CMY value. In other words, the hostapparatus 100 may determine which of the values corresponding to thecolors cyan, magenta, and yellow, respectively, is the highest. The hostapparatus 100 may compare the highest CMY value with the thresholdvalues to determine a region of the pixel and to generate the secondcolor-matching table 531.

FIG. 5D is similar to FIG. 5B, except the closeness of the CMYK pixel toa monochrome color, black, is determined by the highest CMY value eachpixel minus the K value, rather than by an average CMY value. In otherwords, the host apparatus 100 may determine which of the valuescorresponding to the colors cyan, magenta, and yellow, respectively, isthe highest. The host apparatus 100 may then subtract from the highestvalue the K value of the pixel and compare the result with the thresholdvalues to determine a region of the pixel and to generate the secondcolor-matching table 541.

Although examples of methods of generating second color-matching tableshave been illustrated above, any appropriate method may be used,including any combination of the above methods. In addition, while theexample embodiments of FIGS. 5B-5D illustrate analyzing individualpixels, the host apparatus 100 or image-forming apparatus 200 mayaverage or combine any number of pixels to determine whether a portionof a document or the whole document is located within a predeterminedregion. For example, if the host apparatus 100 generates the secondcolor-matching table, the host apparatus 100 may analyze the document todetermine portions having similar color characteristics and maycalculate the second color-matching table corresponding to each of theportions of the document, instead of generating the secondcolor-matching table for each pixel, as illustrated in FIGS. 5B-5D.

FIGS. 9A and 9B illustrate analyzing a document to generate secondcolor-matching tables for different parts of the document. Asillustrated in FIG. 9A, a host apparatus 100 or image-forming apparatus200 may analyze a document to identify similar elements. For example, inFIG. 9A, the graphic 910, text 920, photo 930, text 940, and graphic 950are identified as separate elements. The host 100 or image-formingapparatus 200 may analyze each element to determine whether the elementcorresponds to the first region, as indicated by the referenceidentifier E, the second region, as indicated by the referenceidentifier F, or the third region, as indicated by the referenceidentifier G. In FIG. 9A, text 920 and 940 are identified as being inthe first region E, or the closest colors to a monochromatic color,graphic 910 is identified as being in the second region F, and photo 930and graphic 950 are identified as being in the third region G.

Consequently, the host apparatus 100 or image-forming apparatus 200 maygenerate second color-matching tables to correspond the elements of thedocument that in turn correspond to each of the first, second, and thirdregions. In other words, the host apparatus 100 or image-formingapparatus 200 may generate a second color-matching table correspondingto region 1 and may use the table to form an image corresponding to thetext 920 and 940. Another second color matching table may be generatedto form images of the graphic 910, and yet another second color matchingtable may be generated to form images of the photo 930 and the graphic950.

In FIG. 9B, the host apparatus 100 or the image-forming apparatus 200may analyze the document 900 to determine which portions of the documenthave similar color characteristics, and may generate different secondcolor-matching tables accordingly. For example, the host apparatus 100or image-forming apparatus 200 may determine that the photo 930 includesa monochrome portion 930 a and may associate the monochrome portion 930a with the first region E. Likewise, it may be determined that thegraphic 950 includes a monochrome portion 950 a corresponding to thefirst region E, an intermediate portion 950 b corresponding to thesecond region F, and a high-color portion 950 c corresponding to thethird region G. The host apparatus 100 or image-forming apparatus 200may then associate each portion of the document 900 with a correspondingsecond color-matching table.

In other words, the host apparatus 100 or image-forming apparatus 200may generate a second color-matching table corresponding to the firstregion E to print the text 920 and 940, the portion 930 a of the photo930, and the portion 950 a of the graphic 950. The host apparatus 100 orimage-forming apparatus 200 may generate another second color-matchingtable to correspond to the second region to print the graphic 910, andthe portion 950 b of the graphic 950. The host apparatus 100 orimage-forming apparatus 200 may generate another second color-matchingtable to correspond to the third region to print the remaining elementsof the document.

As described above with respect to the second region and the thirdregion, formation of boundaries between a first region, which is printedby using black only, and second and third regions may be prevented bysetting weights for black and cyan, magenta, and yellow. Furthermore,color-monochrome reversing may also be prevented.

The relative printing values suggested above are mere examples and arenot limited thereto. The second color matching table may be generated byusing various methods.

The control unit 220 stores the generated second color matching table inthe storage unit 230. A second color matching table may be eitherpermanently stored for repetitive application or temporarily stored forone-time application, based on printing options. Furthermore, the usermay update the stored second color matching table.

Furthermore, the control unit 220 may store the second color matchingtable in the host apparatus 100 connected to the image forming apparatus200 or in a storage medium connected to the image forming apparatus 200.The storage medium includes any medium capable of storing data, and thecontrol unit 200 may also store the second color matching table in amobile storage medium connected to the image forming apparatus 200 orthe host apparatus 100. The host apparatus 100 may include a datastorage device (not shown) such as a memory chip, for example, to storethe second color matching table.

Accordingly, the user may perform printing tasks in same printing methodas described above via other image forming apparatuses by using thestored second color matching table.

The selecting unit 222 selects either a first printing method to print adocument to be printed by using the first color matching table or asecond printing method to print the document by using the second colormatching table based on color properties of the document. In otherwords, when the black optimization printing option is activated, theselecting unit 222 selects either the first printing method or thesecond printing method based on how close the values of red, green, andblue of the document are to monochrome values. Furthermore, when thesecond printing method is selected, the selecting unit 222 may selectcolor matching tables corresponding to each of set regions based on howclose the values of red, green, and blue are to monochrome values. Theselecting unit 222 may include a program executed by the control unit220 and the selecting unit 222 may include one or more processors, logiccircuits, and memory to perform the selection operation.

In the first printing method according to an embodiment of the presentgeneral inventive concept, a document is printed by using the firstcolor matching table existing in the image forming apparatus 200. Thefirst color matching table is a color matching table that is stored inthe image forming apparatus 200 in advance and set as the default colormatching table. In other words, when the black optimization printingoption is not set, a printing task is performed by using the first colormatching table according to a general printing procedure. Furthermore,even if the black optimization printing option is activated, a printingtask is performed by using the first color matching table with respectto regions set to be printed by using a first printing method.

In the second printing method, a document is printed by using the secondcolor matching table. The image forming apparatus 200 sets a pluralityof regions in the document to be printed based on the values of red,green, and blue in the document, selects the second color matching tablecorresponding to each of the set regions, and prints the document.

If the document to be printed includes one or more objects such as aphoto object, a text object, and a graphic object, a printing task maybe performed by selecting either the first printing method or the secondprinting method with respect to not only the entire document, but alsoindividual objects. Furthermore, if the document includes one or morepages, a printing task may be performed by selecting either the firstprinting method or the second printing method with respect to individualpages.

The selecting unit 222 may either perform a printing task by selectingthe second printing method with respect to the entire document orindividual objects based on the values of red, green, and blue of thedocument or perform a printing task by selecting either the firstprinting method or the second printing method with respect to the entiredocument or individual objects based on the values of red, green, andblue in the document.

The control unit 220 performs a color matching operation with respect toeach region of the document to be printed by using the first colormatching table or the second color matching table. The second colormatching table may be a color matching table which is generated inadvance and stored in the storage unit 230, the host apparatus 100, or astorage medium, and read out. Furthermore, the control unit 220 mayperform color matching operations with respect to individual objectsduring the color matching operation by using color matching tablescorresponding to each region in the document to be printed.

After the color matching operation is completed, the control unit 220performs a half-tone operation. The control unit 220 outputs data onwhich the half-tone operation is performed to the image forming unit 251and the document to be printed is printed. In the half-tone operation,the control unit 220 improves a seamless appearance of a formed image bycontrolling a size or spacing of image elements, such as dots or pixels,between, around, or within existing image elements. For example, thecontrol unit 220 may improve a shading of a portion of the image byvarying an image element size from a darker portion of the shading inthe image to a lighter portion of the shade in the image.

The control unit 220 obtains RGB images via the communication interfaceunit 210. A data process in the control unit 220 based on selection ofthe black optimization printing option is shown in FIG. 6.

FIG. 6 is a flowchart of a data process performed by the control unit220 based on selection of the black optimization printing optionaccording to an embodiment of the present general inventive concept.Referring to FIG. 6, the flowchart of the data process performed by thecontrol unit 220 according to an embodiment of the present generalinventive concept includes operations that are time-sequentiallyprocessed in the image forming apparatus 200 shown in FIG. 1. Thus, allprevious descriptions in relation to the image forming apparatus 200shown in FIG. 1 also apply to the flowchart of FIG. 6.

In operation S601, the control unit 220 obtains RGB images of a documentto be printed.

In operation S602, the control unit 220 determines whether the blackoptimization printing option according to an embodiment of the presentgeneral inventive concept is executed. If the black optimizationprinting option is activated, the operation proceeds to operation S604.If the black optimization printing option is not activated, the dataprocess proceeds to operation S603.

In the operation S603, the control unit 220 performs a color matchingoperation with respect to the document to be printed by using the firstcolor matching table stored in the storage unit 230.

In the operation S604, if the black optimization printing option isactivated, the control unit 220 determines whether a stored colormatching table exists. The stored color matching table may be stored inone or more of the storage unit 230, the host apparatus 100 connected tothe image forming apparatus 200, and a storage medium connected to theimage forming apparatus 200. If it is determined that the stored colormatching table exists, the data process proceeds to operation S606. Ifit is determined that a stored color matching table does not exist, thedata process proceeds to operation S605.

In the operation S605, the generating unit 221 generates the secondcolor matching table by using color properties corresponding to valuesof red, green, and blue of the document.

In the operation S606, the control unit 220 performs a color matchingoperation by using either the stored color matching table or thegenerated second color matching table.

In operation S607, the control unit 220 performs a half-tone operation,and then the document to be printed is converted to CMYK images.

FIGS. 7A and 7B are flowcharts of data process for an individual objectbased on selection of the black optimization printing option accordingto an embodiment of the present general inventive concept. Referring toFIGS. 7A and 7B, the flowchart of the data process performed by thecontrol unit 220 according to an embodiment of the present generalinventive concept includes operations that are time-sequentiallyprocessed in the image forming apparatus 200 shown in FIG. 1. Thus, allprevious descriptions in relation to the image forming apparatus 200shown in FIG. 1 also apply to the flowchart of FIGS. 7A and 7B.

In operation S701, the control unit 220 obtains RGB images of thedocument to be printed.

In operations S702 through S704, the control unit 220 determines whetherthe black optimization printing option according to an embodiment of thepresent general inventive concept is executed with respect to individualobjects. If it is determined that the black optimization printing optionis executed, the data process proceeds to operations S705 through S707,respectively. If it is determined that the black optimization printingoption is not executed, the data process proceeds to operations S711through S713, respectively.

In the operations S705 through S707, the control unit 220 performs analgorithm according to options to print a document based on colorproperties according to an embodiment of the present general inventiveconcept with respect to individual objects. The algorithm refers to theoperations S604 and S605 shown in FIG. 6. In other words, the algorithmrefers to an operation of determining whether a stored color matchingtable exists or not and either reading out the stored color matchingtable or generating the second color matching table. The generating unit221 reads out the first color matching table stored in the storagemedium 230 and uses the first color matching table to generate thesecond color matching table.

In operations S708 through S710, the control unit 220 performs a colormatching operation with respect to individual objects.

In operations S711 through S713, the control unit 220 performs colormatching operation by using the first color matching table stored in thestorage unit 230.

In operation S714, the control unit 220 performs a half-tone operation,and then a document to be printed is converted to CMYK images.

Thus, the image forming apparatus 200 according to an embodiment of thepresent general inventive concept may determine whether the blackoptimization printing option is executed or not and print with respectto individual objects. A user may set printing options to individualobjects, or printing options may be set to individual objects accordingto default setting of the image forming apparatus 200.

Referring back to FIG. 1, a color matching table which includes mixtureratios of colors to print a document and print data of a document to beprinted may be stored in the storage unit 230. Furthermore, the storageunit 230 may store a new color matching table generated by thegenerating unit 221. The storage unit 230 according to an embodiment ofthe present general inventive concept is a general storage unit, and itwill be understood by one of ordinary skills in the art that examples ofthe storage unit 230 include a hard disk drive (HDD), a random accessmemory (RAM), a flash memory, and a memory card.

The user interface unit 240 obtains a signal input by the user, anddisplays output information to the user. For example, the user interfaceunit 240 may be an input/output device, such as a display panel, amouse, a keyboard, a touch panel, a monitor, and a speaker, that isprepared in the image forming apparatus 200,

The user may activate the black optimization printing option or confirmprinting option setting by using the user interface unit 240.

The image forming unit 251 performs image formation with respect to adocument to be printed obtained from the control unit 220. In otherwords, according to control of the control unit 220, the image formingunit 251 performs a printing task with respect to the document to beprinted based on selection of printing options according to anembodiment of the present general inventive concept with respect to theentire document, individual pages, or individual objects of the documentto be printed. In other words, according to a result of selecting thefirst printing method or the second printing method by the selectingunit 222, print data is printed by applying the first color matchingtable or the second color matching table to the entire document orindividual objects of the document. A printing task may be performed byeither applying the stored second color matching table one time and thendeleting or discarding the second color matching table or an dataaddress of the second color matching table, or the stored second colormatching table may be used repeatedly in subsequent printing operations.

The faxing unit 252 and the transmission performing unit 253 performvarious functions of the image forming apparatus 200. The faxing unit252 performs transmission of a document via fax, and the transmissionperforming unit 253 may perform functions for transmitting a document toan external device, such as a server, a mobile storage medium, and acomputer system.

FIG. 8 is a flowchart of a method of controlling the image formingapparatus 200 which supports the black optimization printing optionaccording to an embodiment of the present general inventive concept.Referring to FIG. 8, the flowchart of the method of controlling theimage forming apparatus 200 includes operations that aretime-sequentially processed in the image forming apparatus 200 shown inFIG. 1. Thus, all previous descriptions in relation to the image formingapparatus 200 shown in FIG. 1 also apply to the flowchart of FIG. 8.

In operation S801, the processor 130 of the host apparatus 100 executesa printer driver to print a document.

In operation S802, a user selects the black optimization printing optionvia the user interface unit 110, and the black optimization printingoption is executed in the printer driver in correspondence to theselection.

In operation S803, the processor 130 generates the second color matchingtable by using the existing first color matching table and colorproperties corresponding to values of red, green, and blue of thedocument based on the black optimization printing option set by usingthe executed printer driver.

In operation S804, the processor 130 selects the first printing methodto print the document by using the first color matching table or thesecond printing method to print the document by using the second colormatching table according to values of red, green, and blue of thedocument by using the executed printer driver.

In operation S805, the communication interface unit 140 transmits printdata to which a color matching table corresponding to the printingmethod selected by using the executed printer driver is applied to theimage forming apparatus 200.

Thus, regions may be set based on how close the values of colors of thedocument are to monochrome values, a color matching table correspondingto the set region may be generated, a printing method corresponding tothe set region may be selected, and a color matching table correspondingto the selected printing method may be used. Further, the printingmethod described above may be controlled by using not only the imageforming apparatus 200, but also the host apparatus 100.

As described above, the image forming apparatus 200 may perform aprinting task with a black toner only with respect to regions of whichcolor values are close to monochrome values by using the blackoptimization printing option. Thus, if a document partially includescolors other than black, only regions of the document having colorsother than black may be printed by using mixed colors and regions havingcolors close to monochrome values may be printed by black only. Thus,printing quality may be improved, and problems such as partially printedtexts and unnecessary use of mixed colors caused by printing black colorby using mixed colors may be resolved. Further, the cost of printingtask can save by preventing unnecessary use of mixed color toners, andthe accurate charging is possible when the cost is charged based ontoner consumption.

The embodiments of the present general inventive concept can be writtenas computer programs and can be implemented in general-use digitalcomputers that execute the programs using a computer readable recordingmedium. Examples of the computer readable recording medium includemagnetic storage media (e.g., ROM, floppy disks, hard disks, etc.), andoptical recording media (e.g., CD-ROMs, or DVDs).

While present general inventive concept has been particularly shown anddescribed with reference to exemplary embodiments thereof, it will beunderstood by those skilled in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present general inventive concept as defined by the appendedclaims. The exemplary embodiments should be considered in descriptivesense only and not for purposes of limitation. Therefore, the scope ofthe present general inventive concept is defined not by the detaileddescription of the present general inventive concept but by the appendedclaims, and all differences within the scope will be construed as beingincluded in the present general inventive concept.

What is claimed is:
 1. A method of controlling an image formingapparatus supporting a black optimization printing option in a hostapparatus, the method comprising: executing a printer driver of theimage forming apparatus; setting the black optimization printing optionin a user interface of the executed printer driver; generating a secondcolor matching table by using an existing first color matching table andcolor properties corresponding to red, blue, and green values of adocument to be printed based on the set black optimization printingoption; selecting a first printing method to print the document by usingthe first color matching table or a second printing method to print thedocument by using the second color matching table, based on the red,green, and blue values of the document; and transmitting the documentand print data of the document to which a color matching tablecorresponding to the selected printing method is applied to the imageforming apparatus.
 2. The method of claim 1, wherein the colorproperties are relative printing values with respect to cyan, magenta,yellow, and black in regions set based on how close values of red,green, and blue are to monochrome values, and the relative printingvalues are weighted values based on a closeness of the values of red,green, and blue of the document to monochrome values.
 3. The method ofclaim 2, further comprising setting a first region, a second region, anda third region in the document based on the closeness of the values ofred, green, and blue to monochrome values, wherein the second colormatching table is generated to correspond to the set regions by usingthe relative printing values, the relative printing values comprise afirst value and a second value, wherein the first value is a weightvalue assigned to cyan, magenta, and yellow values, and the second valueis a weight value assigned to black value, the relative printing valuesof the first region include 100% of the first value and 0% of the secondvalue, the relative printing values of the second region include 70% ofthe first value and 40% of the second value, and the relative printingvalues of the third region include 30% of the first value and 80% of thesecond value.
 4. The method of claim 2, wherein the second colormatching table is generated by using the first color matching table andthe weighted color properties.
 5. The method of claim 1, wherein thesecond printing method is a method of printing by using pure black ifvalues of red, green, and blue are close to monochrome values, whereinthe pure black is not a composite black.
 6. The method of claim 1,wherein either the first printing method or the second printing methodis selected based on information input by a user.
 7. The method of claim1, further comprising storing the generated second color matching table,wherein the stored second color matching table is either temporarily orrepeatedly used.
 8. The method of claim 1, wherein the documentcomprises one or more objects, either the first printing method or thesecond printing method is selected with respect to individual objectsduring the selecting of the first printing method or the second printingmethod, and wherein print data to which either the first color matchingtable or the second color matching table is applied based on theselection is transmitted.
 9. A method of printing a document based on ablack optimization printing option in an image forming apparatusconnected to a host apparatus, the method comprising: receiving thedocument and information regarding the black optimization printingoption from the host apparatus; generating a second color matching tableby using an existing first color matching table and color propertiescorresponding to red, blue, and green values of the document based onthe received information regarding the black optimization printingoption; selecting a first printing method to print the document by usingthe first color matching table or a second printing method to print thedocument by using the second color matching table based on values ofred, green, and blue of the received document; and printing the documentby using the first color matching table or the second color matchingtable according to the selected method.
 10. The method of claim 9,wherein the color properties are relative printing values with respectto cyan, magenta, yellow, and black in regions set based on a closenessof values of red, green, and blue to monochrome values, and the relativeprinting values are weighted values based on the closeness of the valuesof red, green, and blue of the document to monochrome values.
 11. Themethod of claim 10, further comprising: setting a first region, a secondregion, and a third region in the document based on a closeness of thevalues of red, green, and blue to monochrome values, wherein the secondcolor matching table is generated to correspond to the set regions byusing the relative printing values, the relative printing valuescomprises a first value and a second value, wherein the first value is aweight value assigned to cyan, magenta, and yellow, and the second valueis a weight value assigned to black value, the relative printing valuesof the first region include 100% of the first value and 0% of the secondvalue, the relative printing values of the second region include 70% ofthe first value and 40% of the second value, the relative printingvalues of the third region include 30% of the first value and 80% of thesecond value, and the first value and the second value are changeable.12. The method of claim 9, wherein, when the second printing method isselected, the second printing method is a method of printing by usingpure black if values of red, green, and blue are close to monochromevalues, and the pure black is not a composite black.
 13. The method ofclaim 9, further comprising storing the generated second color matchingtable, wherein the document is printed by temporarily or repeatedlyusing the stored second color matching table.
 14. An image formingapparatus connectable to a host apparatus, the image forming apparatuscomprising: a communication interface unit to receive a document to beprinted and information regarding a black optimization printing optionfrom the host apparatus; a generating unit to generate a second colormatching table by using an existing first color matching table and colorproperties corresponding to red, blue, and green values of the documentbased on the received information regarding the black optimizationprinting option; a control unit to control the image forming apparatussuch that print data to which either the first color matching table orthe second color matching table is applied is printed by the imageforming apparatus; a storage unit to store the received document and thegenerated second color matching table; a selecting unit to select afirst printing method to print the document by using the first colormatching table or a second printing method to print the document byusing the second color matching table based on values of red, green, andblue of the received document; and an image forming unit to print thedocument by using the first color matching table or the second colormatching table based on the selected method.
 15. The image formingapparatus of claim 14, wherein the color properties are relativeprinting values with respect to cyan, magenta, yellow, and black inregions set based on a closeness of the values of red, green, and blueto monochrome values, and the relative printing values are weightedvalues based on the closeness of the values of red, green, and blue ofthe document to monochrome values.
 16. The image forming apparatus ofclaim 15, wherein the control unit sets a first region, a second region,and a third region in the document based on a closeness of the values ofred, green, and blue to monochrome values, the generating unit generatesthe second color matching table to correspond to the set regions byusing the relative printing values, the relative printing valuescomprise a first value and a second value, wherein the first value is aweight value assigned to cyan, magenta, and yellow, and the second valueis a weight value assigned to black value, the relative printing valuesof the first region include 100% of the first value and 0% of the secondvalue, the relative printing values of the second region includes 70% ofthe first value and 40% of the second value, and the relative printingvalues of the third region includes 30% of the first value and 80% ofthe second value.
 17. The image forming apparatus of claim 14, wherein,when the second printing method is selected, the image forming unitprints by using pure black if values of red, green, and blue are closeto monochrome values, and the pure black is not a composite black. 18.The image forming apparatus of claim 14, wherein the selecting unitselects either the first printing method or the second printing methodbased on information input by a user.
 19. A host apparatus to control animage forming apparatus supporting a black optimization printing option,the host apparatus comprising: a user interface unit to receiveinformation to set the black optimization printing option by using aprinter driver of the image forming apparatus; a processor to executethe printer driver of the image forming apparatus, to generate a secondcolor matching table by using an existing first color matching table andcolor properties corresponding to red, blue, and green values of adocument based on the selection of the black optimization printingoption, and to select a first printing method to print the document byusing the first color matching table or a second printing method toprint the document by using the second color matching table; and acommunication interface unit to transmit the document and print data ofthe document to which a color matching table corresponding to theselected printing method is applied to the image forming apparatus. 20.The host apparatus of claim 19, wherein the color properties arerelative printing values with respect to cyan, magenta, yellow, andblack in regions set based on a closeness of the values of red, green,and blue to monochrome values, and the relative printing values areweighted values based on the closeness of the values of red, green, andblue of the document to monochrome values.
 21. A method of forming animage, the method comprising: generating a second color-matching tablecorresponding to a first color-matching table, the values of the secondcolor-matching table based on values of a plurality of colors in adocument and the values of the first color-matching table correspondingto predetermined levels of the colors divided into a predeterminednumber of intervals, each interval corresponding to an intensity of eachcolor, respectively; and printing the document using the secondcolor-matching table when the colors in the document are below apredetermined threshold.
 22. The method according to claim 21, whereingenerating the second color-matching table includes assigning a weightto each of the values of the first color-matching table to correspond tothe intensity of each color in the document, such that the values of thesecond color-matching table are the weighted values of the firstcolor-matching table.
 23. The method according to claim 22, wherein thepredetermined threshold includes a plurality of thresholds, andgenerating the second color-matching table further comprises: dividingthe second color-matching table into a plurality of regions defined bythe plurality of thresholds, respectively, the values of each regioncorresponding to a different weight than the values of each otherregion.
 24. The method according to claim 22, wherein the weightincludes a first weight value and a second weight value, the firstweight value corresponds to a percentage applied to the values of thenon-monochrome colors of the first color-matching table to generate thecorresponding values of the colors of the second color-matching table;and the second weight value corresponds to a percentage applied to avalue of the monochrome color of the first color-matching table togenerate a monochrome color value of the second color-matching table.25. The method according to claim 24, wherein the first weight valuedecreases as the values of the colors of the first color-matching tabledecrease, and the second weight value increases as the values of thecolors of the first color-matching table decrease.
 26. The methodaccording to claim 24, wherein the value of the at least one of thecolors of the first color-matching table used to generate a monochromecolor value of the second color-matching table includes an average ofthe values detected in the document of each color of the firstcolor-matching table.
 27. The method according to claim 24, wherein themonochrome color is black.
 28. The method according to claim 21 whereinthe first color-matching table includes values of the colors red, green,and blue.
 29. The method according to claim 21 wherein the firstcolor-matching table includes values of the colors cyan, magenta,yellow, and black.
 30. The method according to claim 21, furthercomprising: determining color intensities of a plurality of regions ofthe document; and printing each respective region of the document usingthe second color-matching table only when the colors in the respectiveregion are below the predetermined threshold.
 31. The method accordingto claim 30, further comprising: printing each respective region of thedocument using the first color-matching table only when the colors inthe respective region are equal to or greater than the predeterminedthreshold.
 32. A method of performing monochrome color optimization, themethod comprising: receiving an input to perform a monochrome-coloroptimization function on a document; generating a second color-matchingtable corresponding to a first color-matching table, the values of thesecond color-matching table based on values of a plurality of colors inthe document and the values of the first color-matching tablecorresponding to predetermined levels of the colors divided into apredetermined number of intervals, each interval corresponding to anintensity of each color, respectively; determining whether the levels ofthe colors in the document exceed a predetermined threshold; andtransmitting the second color-matching table with print data of thedocument only when the colors in the document do not exceed thepredetermined threshold, and transmitting the first color-matching tablewith the print data of the document only when the colors in the documentexceed the predetermined threshold.
 33. A method of printing an image,the method comprising: generating a second color-matching tablecorresponding to a first color-matching table, the values of the secondcolor-matching table based on values of a plurality of colors in adocument and the values of the first color-matching table correspondingto predetermined levels of the colors divided into a predeterminednumber of intervals, each interval corresponding to an intensity of eachcolor, respectively; determining whether the levels of the colors in thedocument exceed a predetermined threshold; and printing the documentusing the second color-matching table only when the colors in thedocument do not exceed the predetermined threshold, and printing thedocument using the first color-matching table only when the colors inthe document exceed the predetermined threshold.